Conventionally, examples of a transformer in which a coil unit is sandwiched between paired cores include a transformer in which a toric coil unit is disposed around a cylindrical protrusion of a pair of ferrite cores called “PQ core”.
Examples of a method for fixing the above-described transformer to a case accommodating a circuit board include a method of pressing one end of a pair of plate springs against a ceiling portion of the core of the transformer and screwing the other end to a screw table provided on the case. However, the above-described fixing method is problematic in that the core easily cracks due to a strong force being locally applied to only a location at which the plate spring is in contact with the core, and thus the fixing method needs to be improved.
Also, the fixing method is problematic in that abnormal noises are generated by air vibration between the ferrite core and the coil due to magnetostriction.
An object of a technique disclosed in this specification is to provide a coil assembly, a structure for attaching a coil assembly, and an electrical connection box according to which a magnetic core is unlikely to crack and abnormal noises are unlikely to be generated.